Float actuated electrical circuit switch



June 21, 1955 'r. OPUSZENSKI 2,711,454

FLOAT ACTUATED ELECTRICAL CIRCUIT SWITCH Filed Nov. 3. 1955 2Sheets-Sheet 1 INVENTOR. TH EO DORE OPUSZENSKI AGENT.

June 21, 1955 T. OPUSZENSKI FLOAT ACTUATED ELECTRICAL CIRCUIT SWITCH 2Sheets-Sheet 2 Filed Nov. 5, 1953 FIG.

INVENTOR. TH EO DORE OPUSZ EN SKI BY ENC (5. JMTY AGENT.

FLOAT ACTUATED ELECTRICAL CIRCUIT SWITCH Theodore Opuszenski, Stamford,Conn., assignor to The Corn Electric Co., Stamford, Conn.

Application November 3, 1953, Serial No. 389,949

2 Claims. (Cl. 200-84) This invention relates to float actuatedelectrical circuit switches and more particularly to float actuatedelectrical switches which are partially or wholly immersed into aliquid. While this invention is subject to a wide range of applications,it is especially suited for use with inflammable liquids where theelectrical circuit contacts must be shielded from explosive vapors.

Float actuated electrical switches are well known in connection withliquid filling operations. When controlling the level of inflammableliquids, magnetic means are frequently employed to transmit the motionof the float to the actuating means of an electrical switch which ishoused in a fluid tight chamber. The electrical switch actuated is thecontrolling means for the filling pump, for an alarm or signalingdevice, or for a similar con trol device. Switches of this type andpresently used are comparatively large in physical size and burdenedwith an undue amount of mechanical linkage elements. It is diflieulttherefore, to use such switches in confined spaces or in locations wherespace is at a premium, for instance in airborne equipment. Stillfurther, large size structures are adversely affected by vibration,becoming unreliable and inaccurate.

One of the objects of this invention is to provide an improved floatactuated electrical circuit switch which avoids one or more of thedisadvantages of prior art arrangements.

Another object is the provision of a switch of the character describedwhich is of small physical dimensions and of compact construction thusbeing suited for use in confined spaces.

Another object of this invention is the provision of a float actuatedelectrical switch which because of its few parts is easy to manufactureand of economical construction.

A still further object of this invention is to provide a switch whichmay be used for expendable purposes.

Another and further important object of the invention is the provisionof a float actuated electrical circuit switch which is equipped withadjustable calibrating means for precise liquid level control.

One of the features of this invention includes a float actuatedelectrical circuit switch which comprises an enclosure adapted to beimmersed into a liquid. A first magnetic means and an electrical circuitswitch are disposed inside of the enclosure. The first magnetic means issupported for pivotal motion relative to said enclosure and said switch.Lever means between the first magnetic means and the actuating means ofthe switch cause switch actuation as a result of pivotal motion of saidfirst magnetic means. A second magnetic means and a float are disposedoutside of said enclosure and are mounted for pivotal motion in unisonabout the enclosure. The first and second magnetic means form a magneticcircuit causing the first magnetic means disposed inside of theenclosure to move in response to the motion imparted to the secondmagnetic means which is disposed outside of the enclosure.

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For a better understanding of the present invention together with otherand further objects thereof, reference is made to the followingdescription taken in connection with the accompanying drawings in which:

Figure 1 is a side elevation, partly in section;

Figure 2 is a plan view with housing sectioned;

Figure 3 is an enlarged side elevation of certain working parts;

Figure 4 is a top view showing the bracket in which one magnet pivots;

Figure 5 is the same view as Figure 3 with certain parts in shiftedposition; and

Figure 6 is a sectional view at 6-6 of Figure 3.

Referring now to the figures, numeral 10 identifies a fluid tightchamber which is formed by a two-piece enclosure, namely back plate 11and a bell shaped housing 12. Housing 12 and back plate 11 are joined influid tight relation by means of a gasket 13 and screw means (notshown). It is understood that other sealing means including brazing,welding, soldering, plastic resins etc. may be used to accomplish afluid tight enclosure. Within this fluid tight enclosure there isdisposed a stationary electrical circuit switch 14 supported from theback plate 11 by a bracket 16, and also a first permanent magnet 15which is mounted for pivotal motion relative to housing 12 by virtue ofpivotal stud 17 supported in bracket 16. Magnet 15 is retained on stud17 by means of a magnet bracket 18 which pivots in unison with themagnet about the central axis of stud 17. Switch 14 is a push buttonactuated snap action switch, frequently termed microswitch. As magnet 15is caused to pivot about the central axis of stud 17 (source of motionwill be described later) lever means, which include arm 2%? supportedbetween stationary pin 21 and pin 22 attached to movable magnet bracket18, cause switch actuation by engaging the actuating push button 23 ofthe electrical circuit switch 14.

Two pivoting studs 25 and 25 are fastened to the outside of the housing12 but do not penetrate to the inside of the enclosure so as not topuncture the fluid tight chamber. These studs are adapted to pivotallysupport a float bracket connected to a float 31, and also a magnetbracket 32 which holds a second permanent magnet 33 and magnet retainingstud 34. The float 31 and magnet 33 are mounted for pivotal motion inunison by virtue of screw stud it; which retains a bracket extension 41attached to float bracket 30 in fixed distance with respect to anextension 42 attached to magnet bracket 32. A flange riveted locknut 43and pin 4-: are used to secure the position of stud with respect to thebracket extensions 1 and 4-2 respectively. Locknut 43 preferably is ofthe pressure engaging type having a yieldable insert, commonly known aselastic stop nut.

Magnets 15 and 33 are disposed opposite each other and arranged withcomplementary pole notation, i. e. a magnetic circuit with attractingforces between both magnets. In order not to diminish the magnetic forcebetween the magnets, the curved portion of the housings 12 disposedbetween the magnets and about which the magnets pivot, is madepreferably of substantially non-magnetic material.

In the preferred embodiment, studs 25 and 26 are positioned upon theexterior of housing 12 in such a manner that they are in alignment withstud 17, resulting that both magnets pivot about a common axis tomaintain constant gap distance.

The float actuated switch structure described above is mounted by meansof threaded fitting 6t) and nut 61 inside of a tank which is adapted toretain the liquid whose level is to be controlled. The electricalconductors 62 leading from the switch 14 are brought to the exterior ofchamber 10 in fluid tight relation by means of sealing gasket 63. Ahousing 64 supported on fitting 6% serves to provide not only mechanicalprotection for the exposed active parts (float and magnet), but isadapted also to limit the pivotal motion of float 31. This feature isparticularly advantageous when excessive mechanical vibration isencountered or when the liquid level exceeds the control limits of theswitch.

In operation, the liquid of the tank communicates with the fioat andwith the outside of the fluid tight enclosure by means of the largeaperture 70 of the housing 64. As the liquid level rises, the floatpivots in counterclockwise direction carrying along magnet 33. Thismagnet transmits its motion to the inside of the fluid tight chamber byvirtue of its interlinking magnetic circuit with magnet 15. Magnet 15thus is caused to follow the motion of the outer magnet (Figure and thelever arrangement between magnet and switch 14 causes switch actuationwhen a predetermined pivotal position is reached. This switch actuationmay be used to control the electrical circuit of the pump motor, to

cause the operation of an alarm circuit, or the operation of some othersuitable control means.

In order to accurately adjust the switch actuation relative to theliquid level desired, adjusting screw 40 is rendered accessible from theoutside of housing 64 via aperture 71. An adjustment of this screw studchanges the fixed position of float 31 relative to the associated magnet33, thus obtaining a convenient method for precise liquid level control.It will be apparent also that this adjusting means serves to provideconvenient calibration means for factory adjusted and readilyinterchangeable float actuated electrical circuit switches.

Although the foregoing description and illustrations show the use of twopermanent magnets, it will be apparent that a single magnet and anopposing member made of magnetizeable material will perform in a satisfactory manner. Still further, the magnet shown and described may bereplaced by an electromagnet Without departing from the principle of theinvention.

The fluid tight chamber which contains the electrical switch may beimmersed into inflammable liquids without danger of explosion since theopening and closing of electrical contacts is separated from the liquiditself.

It will be observed that the structure disclosed is devoid of longlevers and complicated mechanical motions and moments. The adjustingmeans between the float and associated magnet permit precise control ofswitch actuation over a wide range of liquid levels. The construction iscompact and characterized by a minimum number of moving parts, thusrendering the switch mechanism suited particularly for airborneequipment. The small size of the individual components, the ruggedconstruction and the short pivotal motions cause the float actuatedswitch to be inherently insensitive to mechanical disturbances, such asthe eifects of vibration, shock, acceleration, rough handling, etc. Theeconomical manufacture of the disclosed construction, caused as a resultof the small quantity of individual parts, ease of assembly, andsimplicity of adjustment and calibration after final assembly, permitsthis float actuated switch to be used for expendable fuel tanks andsimilar devices which are becoming evermore significant.

While there have been described and illustrated specific embodiments ofthe invention, it will be obvious to those skilled in the art thatvarious changes and modifications may be made therein without departingfrom the spirit and field of the invention which should be limited onlyby the scope of the appended claims.

What is claimed is:

1. A float actuated electrical circuit switch comprising a fluid tightenclosure adapted to be immersed into a liquid, at first permanentmagnet and an electrical circuit switch disposed inside of saidenclosure, said first magnet supported for limited pivotal motionrelative to said enclosure and said switch, lever means between saidfirst magnet and the actuating means of said switch to cause switchactuation as a result of pivotal motion of said first magnet, a secondpermanent magnet and a float disposed outside of said enclosure andmounted for pivotal motion in unison about a substantially nonmagneticportion of said enclosure, said first and second magent being spacedapart with complementary opposing pole faces to form a magnetic fieldwith attracting forces between said magnets to cause said first magnetto move in the same direction as said second magnet when impartingmotion to said second magnet, the pivotal axes of both magnets beingsubstantially coincident to maintain uniform gap distance between saidpivotally moving magnets, screw adjusting means disposed between saidsecond magnet and said float for adjusting the relative positiontherebetween, a housing supported by said enclosure and shaped to extendover a portion of said float, said housing equipped with a firstaperture to permit communication between the liquid and said float andwith a second aperture to permit communication between the outside ofsaid housing and said screw adjusting means and said housing beingadapted to limit the pivotal motion of said float.

2. A float actuated electrical circuit switch comprising a fluid tightenclosure adapted to be immersed in a liquid, a first permanent magnetand a snap acting electrical circuit switch disposed inside of saidenclosure, said first magnet supported for limited pivotal motionrelative to said enclosure and said switch, lever means between saidfirst magnet and the actuating means of said switch to cause switchactuation as a result of motion of said first magnet, said lever meansincluding an arm supported between a stationary pin and a magnet motionresponsive movable pin, a second permanent magnet and a float disposedoutside of said enclosure and mounted for limited pivotal motion inunison about a substantially non-magnetic portion of said enclosure,said first and second magnet interconnected by magnetic force whichcauses said first magnet to move in response to motion imparted to saidsecond magnet, the pivotal axes of both magnets being substantiallycoincident to maintain uniform gap distance between said magnets, screwadjusting means disposed between said second magnet and said float foradjusting the relative position therebetween, a housing supported bysaid enclosure and shaped to extend over a portion of said float, saidhousing equipped with an aperture to permit communication between theliquid and said float and an aperture to permit communication betweenthe outside of said housing and said screw adjusting means, and saidhousing being adapted to limit the pivotal motion of said float.

References Cited in the file of this patent UNITED STATES PATENTS1,615,647 Pierce et al Jan. 25, 1927 2,255,732 Kronmiller Sept. 9, 19412,356,652 Connolly et a1. Aug. 22, 1944 2,577,165 Thorsheim Dec. 4, 19512,596,666 Edgar et al. May 13, 1952

